1. Field of the Invention
The present invention relates to a catheter's system that can be used for infusion of fluids (drugs, water and nutrients) to the body, with concurrent aspiration of biological material (blood, pus, pathological tissue, toxic substances) from the body, in human and, or, animal tissue, without any blockage problems.
2. Description of the Related Art
There are many kinds of catheters which are used for fluid infusion and aspiration in a clinical or preclinical setting. Traditionally, the catheter's tip that is inserted in biological material, is called “distal” and the tip that stays outside is called “proximal”.
Most of existing catheters have a single lumen and through this lumen the user can alternatively infuse or aspirate liquids.
For example, in a clinical setting, the common intravenous catheter either aspirates blood samples—usually immediately after it's insertion to the vein—or infuses solutions of drugs and, or, nutrients—usually for many hours or days following insertion.
These catheters can infuse or aspirate large quantities of liquids, but they cannot do it concurrently in order to have a constant exchange of drugs and nutrients with the extra-cellular fluid or pathological liquid accumulations of the tissue.
The concurrent fluid exchange is desirable both for monitoring and therapeutic reasons.
There are few catheters with multiple lumina, which can concurrently infuse and aspirate liquids.
For example, the microdialysis catheter after its introduction to a human or animal tissue, is continuously perfused with liquid solutions from a pump connected to its proximal tip. The catheter consists of two concentric lumina, or tubes, that are covered at their distal tip by a membrane. Usually the central tube is the efferent and the peripheral tube is the afferent part of the catheter. Part of the perfused liquid is infused to the tissue through the catheter's membrane at its distal end, and extra-cellular fluid is aspirated through the same membrane and the efferent lumen.
Microdialysis catheters and similar catheters, however, were designed for tissue monitoring, and the above described concurrent infusion and aspiration takes place at a few microliter/minute rate flow range and through very small membrane pores.
For therapeutic applications we need much greater liquid exchange rate and membranes or cages with big pores so that it is possible to evacuate low viscosity liquids like pus, that block all existing catheters.
A common problem of all kinds of existing catheters for biological fluids, is their blockage, due to corking of biological material into their lumen's tip or it's covering.
For example, the endotherapy catheter system claims to possess the desired liquid exchange rate and blockage free operation through a moving part.
It consists of two concentrical tubes, one infusing and one aspirating, connected properly to infusion and aspiration devices at their proximal tip, and having a filter or membrane or grid or mesh cage covering their distal tip, which contains an hydrodynamically moving device for concurrent infusion and aspiration. The infusing tube is appropriately connected to a moving device that irrigates the surrounding the catheter space, while simultaneously propels with its movement the aspiration through the other tube.
The following documents are considered the most relevant state of the art as mentioned above:
D1: U.S. Pat. No. 4,694,832 (UNGERSTEDT CARL U) 22 Sep. 1987
D2: U.S. Pat. No. 4,755,175A (NILSSON LEIF) 5 Jul. 1988
D3: PCT/GR2004/000045, IPC A61M 25/00, (PANOTOPOULOS CHRISTOS), 8 Sep. 2003.